Finger guard mechanism for jointers



July 21, 1959 H. s. RHETT 2,895,517

FINGER GUARD MECHANISM FOR JOINTERS Filed April 11, 1957 2 Sheets-Sheet 2 IN VENTOR ATTORNEY-9 Unite States 2,895,517 FINGER GUARD MECHANISM FOR JOINTERS Haskell S. Rhett, Wilmington, N.C.

Application April 11, 1957, Serial No. 652,151 Claims. or. 144-251 This invention relates to a cutterhead guard such as is particularly adapted for use in connection with the cutterhead of a conventional jointer though by no means restricted to such use.

The most commonly known guard now in use with a jointer cutterhead comprises a guard plate swingable in a horizontal plane over the cutterhead. Such a guard plate is generally yieldably urged toward the fence of the jointer in such manner that feeding movement or traverse of the workpiece over the cutterhead will urge the guard in the direction of feed in a manner to swing it away from the fence sufficiently to permit entry of the workpiece.

Such a guard has certain disadvantages. Foremost of these is that it does not close over the cutterhead until after the workpiece has completed its traversal of the cutterhead and between the guard place and fence. This results in leaving the cutterhead uncovered and the guard thus inoperative during the period when it is most needed, since it is at this time that the operators fingers, in pushing the rear end of the workpiece over the cutterhead, are most likely to be exposed to injury by the cutterhead. Moreover, such conventional type of guard, due to its aforementioned mode of operation, can be pushed aside by the fingers of the operator in feeding the workpiece, thereby'permitting the fingers to engage the cutterhead. In addition, such prior guard plates have almost completely obscured the cutterhead from view so that it has been practically impossible to watch the progress of the out being made unless the guard plate is pulled aside for this purpose with resultant risk of injury. Due in large part to this latter feature such guard plates of the prior art havefrequently been removed or placed in inoperative position by operators who would prefer to incur the risk involved in working without them rather than tolerate the inconvenience caused by them.

With the foregoing considerations in mind the present invention comprises a guard which is projected toward the workpiece transversely to the feed movement of the workpiece and restrained from movement with the workpiecein such manner that it cannot be retracted by engagement with the operators fingers incident to moving the workpiece acrossthe cutterhead. Moreover, in its preferred. embodiment the invention comprises a main guard. or guard element disposed slightly in advance of the. cutterhead, which is spring projected to close behind the rear end of, the workpiece and. toward the fence to prevent the operatorsfingers from moving into contact with the cutterhead, this action occurring immediaely following passage of the rear end of the workpiece beyond the main guard.

. A further highly important feature of the invention con sists irrthe provision of one or more, preferably a plurality, of auxiliary guide fingers or plungers which are carried by the main guard, these being individually spring projected toward the fence and overlying the cutterhead to guard same against Contact by the operators fingers. These guard fingers are preferably spaced apart in the direction of feed of the workpiece to permit a clear view of the cutterhead and of the out being made, and are Patented July 21, 1959 ice individually spring projected toward the fence in such manner that they may successively be projected toward the fence past the rear end of the workpiece during pro gressive movement of the latter over the cutterhead.

It is an important feature of the invention that the main guard is spring projected toward the fence with a force which is greater than the forces collectively exerted by the spring projecting means associated with the feed fingers, all to the end that, following movement of the workpiece beyond the contacting portion of the said guard, the latter may be spring projected toward the fence, the guard fingers being relatively retracted by continued engagement with the workpiece and being thereafter successively projected as the workpiece moves past them.

Thus, it will be apparent that the invention includes as its objects: to afford maximum visibility of the cut being made while attaining a continuous highly efficient guard function, and to provide a positive safety stop for engagement with the operators fingers to prevent them from moving into engagement with the cutterhead.

Additional features consist in the disposition of cam means on the main guard permitting entry of the workpiece for engagement with the cutterhead either in the longitudinal direction of feed of the workpiece or in a downward direction transverse to the feed, whereby the workpiece may be engaged with the cutterhead for any portion of its length for planing off high spots or irregularities. Also, in accordance with the invention, the guard is preferably arranged so that it may be displaced easily to an inoperative position to facilitate sharpening of the cutterhead and to permit rabbetting operations in usual manner.

The foregoing objects and advantages are attained by the preferred embodiment of the invention illustrated in the accompanying drawing in which:

Figure l is a plan view of a conventional jointer incorporating the invention in its preferred form.

Figure 2 is a front elevation of the structure of Figure 1.

Figure 3 is a section on the line 3-3 of Figure 2.

Figures 4 and 5, respectively, are'identical fragmentary plan views showing the relative positions assumed by the guard structure during different stages of the traverse of the workpiece.

Referring now in detail to the accompanying drawings, the invention is there illustrated in its preferred application to a generally conventional jointer. The jointer comprises a conventional infeed table 10 and outfeed table 11 in relative longitudinal alignment, between which is rotatably supported a usual cutterhead 12, the latter being rotatable about a horizontal axis traverse to the tables 10 and 11, as well as to the usual fence 13, which is disposed longitudinally over both tables along the rear longitudinal edges thereof. Normally the cutterhead 12 has its upper periphery on the same level as the top of the outfeed table 11 and slightly above the level of the infeed table 10, this difference in levels as between the infeed table and the upper periphery of the cutterhead determining the depth of the cut. It will be understood that the workpiece generally designated W is normally placed on the infeed table with one side thereof in abutting engagement with the fence 13 and is manually fed along the fence 13 and over the cutterhead 12 onto the outfeed table 11. The height of the infeed table may be adjusted by any conventional means to vary the depth of the cut and the fence 13 may be angularly adjusted in conventional manner about an axis parallel to its lower edge. However, since the means for accomplishing these adjustments are purely conventional ones and constitute no part of the instant invention they are not illustrated in the accompanying drawings.

The tables and 11 may be suitably supported in horizontal planes by means such as the depending legs 14 projecting upwardly from a base 15 which in turn is bolted or otherwise secured on a horizontal bench 16.

The invention in its preferred application to such a conventional jointer structure comprises a main guard or guard plate 17 which is supported over the infeed table 10 at the infeed side of the cutterhead 12, preferably with its free end portion slidably supported on said table 10 for movement transversely to the fence 13. Suitable means for so supporting the guard 17 and for restraining it against longitudinal movement with the workpiece is exemplified as comprising a swingable arm 18 which is trunnigned at 19 to a bracket 20 bolted on the base 15 as at 21 The guard 17 has its rear end hingedly con nected by longitudinal pintles 22 to the upper end of said am a e i i nt mean exempli d by he p in 23 connected under tension between opposite sides of; the arm 18 and the infeed table urges the guard 17 resiliently toward the fence '13., whereby its operative free end 17' may be normally retained in slidable abutting engage ment with the workpiece W as the latter is fed over the cutterhead.

Although the fence 13 may be relied upon for limiting the movement of the guard 17, it is preferred to utilize an adjustable limit stop such as the set screw 28 threaded through the depending hinge knuckle 2d of the guard plate with its end positioned for abutting engagement with the adjacent edge of the infeed table 10. A usual lock nut 25 may function to secure the screw 28 in any desired position of adjustment. The adjustment of the screw 28 will normally be such as to permit only a very slight clearance between the fence 13 and the free end 17' of the guard in the fully projected position of the guard.

In order to provide for retraction of the guard 17 incident to engagement with the workpiece during its traverse, to permit entryof a workpiece W between the guard and the fence 13, the guard will be provided with a cam edge or means 26 inclined in a horizontal plane converging toward the fence 13 in the direction of feed of the work- It is further desirable to permit entry of the workpiece by movement in a downward direction, whereby the workpiece W may be engaged with the cutterhead at any desired portion of its length for the purpose of removing high spots and the like. In order that-this may be done without requiring manual retraction of the guard there is provided an upstanding retraction cam 27 at the. free end of the guard having a cam edge 27 inclined or curved in a vertical plane generally converging downwardly toward the fence 13. This cam 27 preferably has a vertical abutment face 27:; (Fig. l) directed away from the cutterhead to serve as a positive stop for engagement with the operators fingers and is otherwise adapted to prevent movement of the operators fingers over the cutterhead with the workpiece, as will be brought forth more fully hereinafter.

Carried by the guard 17 for movement over the cutterhead toward and transversely to the fence 13 are one or more, preferably a plurality, of spring projected guard fingers or plungers 30. In the preferred form of the invention these fingers 30 are slidably disposed and guided through the opposite ends of a housing 31 mounted on a laterally offset base portion 17b of the guard and movable in a direction generally parallel with the rotational axis of the rotary cutterhead 12. Spring means for resiliently individually projecting each of the fingers 30 into operative engagement with the workpiece W may comprise a coil spring 32 disposed about each such finger 30 within the casing 31 and compressed between one end of the casing and a fixed radial abutment or flange 33 on each such finger. It will be seen that the flange 33 of each such finger will be urged toward and into abutment with the front end of the casing. Thus the flanges 33 in conjunction with said front end exemplify means for limiting the projection movement of the respective fingers.

It will be seen that the flanges 33 are so disposed on the fingers 30 that the fingers, when fully projected, have their free ends substantially co-terminus with the free end 17 of the guard and in any event do not project beyond such free end of the guard. This relationship is, of course, necessary in order to cause retraction of the fingers together with the guard incident to the entering of a workpiece between the guard and the fence and in order to prevent the fingers from interfering with the feeding movement of the workpiece into engagement with the cutterhead as the leading end of the workpiece moves past the said free end 17' and toward the cutterhead.

It is to be particularly noted that the several springs or spring means 32 of the respective fingers 30 are collec tively weaker than the resilient means or springs 23 which urge the guard 17 in its entirety toward the fence 13, so that the. springs 23, have an overpowering rela tionship to the springs 32. Thus, near the completion of the feed movement of a workpiece over the cutterhead, as the trailing end of the workpiece passes the free end 17 of the guide the springs 23 will fully project the guard to the extent permitted by its associated stop means 28 so that the guard will immediately close behind the trailing end of the workpiece. Such projection move ment of the guard 17 in its entirety then causes a retraction movement of the fingers 30 resulting from their continued engagement with the workpiece.

In the operation of the invention it will be seen that in the normal feeding of a workpiece W over the cutter-. head 12, the workpiece is placed on the infeed table 10 against the fence 13 and moved manually toward the cutterhead until it engages the cam edge 26 of the guard. The resulting eoaction between the edge 26' and the workpiece during continued movement of the workpiece will force the guard and also its several associated guard fingers 30 away from the fence sufficiently to permit the continued feeding of the workpiece. It will, of course, be noted that the fully projected fingers 30 are arranged to be retracted together with the guard and thus to clear the workpiece as the latter moves past the free end 17' of the guard.

The guard 17 will be maintained in spring projected engagement with the workpiece as the latter is moved over the cutterhead and the several fingers 30 will have their free ends slightly clearing the workpiece until after the trailing end of the workpiece has moved past the free end 17". At this time the guard 17 'will be spring projected behind the rear end of the workpiece to its fully projected position, carrying with it the combined cam and abutment member 27, which will have effectively prevented movement of the operators fingers therepast with the workpiece up to this time, and which at this time will function to effectively pin the operators fingers against the fence 13 in the event the operator should be pushing the workpiece over the cutterhead by means of r a finger abutting against its rear end.

During all this time the location of the guard or guard plate 17 in advance of the cutterhead 12 and the relative spacing of the several guard fingers 3 0 which overlie the; cutterhead will have permitted a clear view of both the cutterhead and of the out being, made, by it onthe workpiece.

The. full projection or closing of the, guard 17 as above mentioned behind the trailing end of the workpiece leave the free ends of the fingers 30 in abutting engagement with the workpiece, these being slightly retracted due to the overpowering relationship of the springs 23 relative to the several finger projecting springs 32.

However, continued movement of the workpiece over. the cutterhead as the cut is completed result in; the.

several fingers 30 being successively and progressively projected to. close behind the trailing, end of the work; piece as. the workpiececlears each. of. them in turn.

Thus, the guard 17 itself and its several co-acting fingers 30 cooperate to successively close behind the workpiece in such manner as to maintain the cutterhead covered at all times and particularly near the completion of the traverse of the workpiece over the cutterhead at which time the most danger will obviously be encountered.

Due to the high visibility of the cutterhead and workpiece afforded by the guard mechanism of the invention, and the lack of interference thereof with the use of the cutterhead, it has been found in practice that the guard mechanism of the invention will be continuously used by the machine operators and will not be moved to inoperative position or discarded as is sometimes the case with other types of guards.

Not only can a cut be made in the manner above mentioned, but where it is desired to remove high spots from the workpiece in order to attain a straight edge it is possible to enter that portion of the workpiece containing the high spot directly into engagement with the cutterhead by moving it downwardly between the fence 13 and the cam element 27, whereby its engagement with the cam surface 27 will cause retraction of the guard 17 and its several fingers 30.

By virtue of the particular manner of mounting the guard 17 for movement toward and retraction from the fence 13 in the preferred embodiment, it will be apparent that the guard may easily be swung about its pivot 22 and thus removed to an inoperative position to permit ready access to the cutterhead for sharpening or replacement. Also, it will be apparent that in such preferred form of mounting, the free end portion of the guard 27 will be slidably supported for movement across the infeed table and will readily adapt itself to various adjusted positions of the infeed table, since it will be raised or lowered with the table without affecting the cooperative relationship between these two elements. In this connection it will be noted that the medial portion of the guard 17 preferably has substantial clearance above the table sutficient to permit the entire operative range of movement of the table.

Although the mounting means herein described has certain novel features as above mentioned, the invention also is capable of use with other types of mountings which provide for guiding the guard 17 transversely to the fence 13 while restraining it from movement in a direction parallel to the fence. Obviously various such forms of mounting will suggest themselves to those schooled in the art.

In this application I have shown and described only the preferred embodiment of the invention simply by way of illustration of the preferred mode contemplated by me of carrying out the invention. However, it is to be understood that the invention is capable of other and different embodiments and that its several details may be altered in various ways in addition to those specifically pointed out above, all without departing from the inven tion. Accordingly the drawings and description herein are to be construed as merely illustrative in nature and not as restrictive.

Having thus described my invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a machine of the class wherein a workpiece is traversed over an infeed table and on to an outfeed table alongside a fence common to both tables for operative engagement with a cutterhead rotatably supported be tween the tables on one side of said fence, the combination comprising a main guard guided for generally horizontal movement over the infeed table transversely to the fence, said main guard being positioned in advance of the cutter head for engagement by the workpiece before the latter is fed into engagement with the cutter head, resilient means urging said guard toward the fence, a plurality of generally parallel horizontal guard fingers carried by the guard for movement thereon transversely to the fence, said fingers normally overlying said cutterhead and being spaced apart in a direction parallel to the fence, spring means resiliently individually projecting said fingers transversely toward said fence, said spring means collectively being weaker than said resilient means.

2. The combination of claim 1 including means associated with said fingers for preventing their projection toward the fence beyond said main guand.

3. The combination of claim 1 including horizontally directed cam means on said main guard positioned for engagement by a workpiece during traversal of the latter along said fence to retract said guard and said auxiliary guard fingers from the fence, means being associated with said fingers for preventing their projection toward the fence beyond said cam means.

4. The combination of claim 1 including an upwardly projecting supporting arm mounted on said machine beside said table for swinging movement about an axis at its lower end extending parallel to said fence, the end of said guard remote from said fence being pivotally connected to and supported by said arm, and the end portion of said guard adjacent said fence being slidably supported on said table.

5. In a jointer of the class wherein a workpiece is traversed along a longitudinally disposed guide fence for operative engagement with a cutterhead rotatably dis posed between infeed and outfeed tables, the combination comprising a main guard having a free end directed toward said fence, means supporting said guard over the infeed table for movement transversely to the fence and restraining it from longitudinal movement, resilient means urging said guard toward the fence, cam means on the guard positioned for engagement by a workpiece during its traverse along the fence to retract said guard from the fence, a plurality of relatively parallel guard fingers carried by the guard for movement over the cutterhead transversely to said fence, means carried by the guard for preventing such movement of the fingers toward the fence beyond said cam means, and spring means resiliently individually projecting said fingers toward said fence, Said spring means collectively being weaker than said resilient means to permit projection of the guard beyond the trailing end of the workpiece at the completion of its traverse, said spring means then successively projecting the respective fingers beyond said trailing end of the workpiece.

References Cited in the file of this patent UNITED STATES PATENTS 65,347 Clark June 4, 1867 552,610 Fisher Jan. 7, 1896 1,126,151 Woodford Jan. 26, 1915 1,394,499 Ingstrum Oct. 18, 1921 2,328,244 Woodward Aug. 31, 1943 FOREIGN PATENTS 100,350 Austria June 25, 1925 

